Attention has been focused on technologies to provide synthetic fibers and the like with exothermic functions due to sorption (sorption exothermic function; function of simultaneously causing absorption and adsorption to generate heat), as well known in clothing such as wool, to allow the fibers and the like in themselves to generate heat and to enhance thermal-insulation effects. The technologies have been applied not only to fibers but also to cotton-like articles, woven fabrics, knitted fabrics, non-woven fabrics, or the like. Furthermore, there have been also attempted various applications such as applications of processing the fibers, the cotton-like articles, the woven fabrics, the knitted fabrics, the non-woven fabrics, and the like with coating agents in which powdery sorption exothermic materials are dispersed, applications of dispersing the fibers, the cotton-like articles, the woven fabrics, the knitted fabrics, the non-woven fabrics, and the like in films, and applications of forming the fibers, the cotton-like articles, the woven fabrics, the knitted fabrics, the non-woven fabrics, and the like into sheet-like articles or paper. Thus, the technologies to suitably evaluate sorption exothermicity are important for promoting the development of high-value-added products.
In recent years, a method comprising, first, preconditioning a collected test piece, putting the absolutely dried test piece in a desiccator, further leaving the test piece standing to stabilize the temperature and humidity of an atmosphere in the desiccator and to also stabilize the temperature and moisture content of the test piece, thereafter carrying out release of the lid of the desiccator, or the like, to expose the test piece to a high-humidity atmosphere, and measuring the surface temperature of the test piece with a temperature sensor has been mainstream as a technology well known as a method of testing sorption exothermicity.
For example, Patent Literature 1 describes an apparatus and a method which measure an exothermic material by adsorption heat and thermal conductivity. Specifically, there has been disclosed an apparatus for measuring sorption exothermicity comprising a precise and prompt thermophysical property measurer, a measurer that measures temperature and the like, a water supplier comprising a pump and the like, and an air supplier, wherein both of temperature increased due to adsorption heat and apparent thermal conductivity can be measured.
Patent Literature 2 also describes a method and apparatus for testing exothermicity due to sorption. Specifically, there has been disclosed a method comprising laterally partitioning a reaction vessel into three by two test pieces to make one central compartment and two side compartments, setting the humidities of atmospheres in the three compartments at initial conditions, thereafter changing the atmosphere in the central compartment or in each of the side compartments to a test condition, simultaneously measuring the temperatures of the two test pieces or the vicinities thereof, and evaluating exothermicity due to the sorption of the test pieces.